The present invention relates to a disk drive apparatus for reading/writing information from/onto a disk-shaped storage medium (hereinafter referred to simply as a xe2x80x9cdiskxe2x80x9d), such as an optical disk, a magnetic disk, and a magneto-optical disk, by using a pickup. More particularly, the present invention relates to a disk drive apparatus capable of cooling the pickup.
In recent years, there has been an increasing demand for reducing the power consumption of a disk drive apparatus, due to the growing popularity of portable equipment using a disk drive apparatus and in view of the environment protection. A significant factor, among others, that increases the power consumption of a disk drive apparatus is the power consumed by the motor (disk motor) for rotating the disk.
In order to reduce the power consumption of a disk motor, it is important to reduce the windage loss, i.e., the load of an airflow generated by the rotation of the disk. When the disk is rotated, airflow is generated in the vicinity of the disk surface because the air surrounding the disk surface moves together with the rotating disk. The air flow gives some air resistance on the rotating disk surface. Furthermore, the disk rotates while slightly wobbling up and down. Therefore, the rotating disk takes relatively large air resistance. As the rotating disk takes the load of the surrounding air (or an airflow), the disk motor also takes some load, which increases the power consumption of the disk motor. Therefore, in order to reduce the power consumption of the disk motor, it is important to reduce the windage, loss on the rotating disk. In order to reduce the windage loss, it is effective to reduce the rotational speed of the disk, for example.
One approach known in the art to minimize the rotational speed of the disk while sufficiently retaining the performance of the apparatus, such as the data transfer rate, is to employ a CLV (Constant Linear Velocity) method for controlling the rotational speed of the disk. In the CLV method, the rotational speed of the disk is lower when reading/writing data from/onto a region of the disk closer to the outer periphery thereof, and higher when reading/writing data from/onto a region of the disk closer to the inner periphery thereof. The CLV method is suitably used with disk drive apparatuses for performing continuous reading/writing operations with little seek operation, such as music CD players. DVD-RAM writing/reading apparatuses suitably employ a ZCLV (Zoned CLV) method, in which different disk rotational speeds are used for a plurality of zones that are defined on the disk surface at different distances from the center of the disk, respectively. With these methods, it is possible to read/write information at a predetermined data transfer rate irrespective of the position of the pickup on the disk. Moreover, since the disk is rotated at the lowest rotational speed required to obtain the predetermined data transfer rate, the power consumption of the disk motor can be reduced.
When the disk drive apparatus is not writing/reading information (i.e., during an idling period), the disk drive apparatus is typically put in a sleep mode (power save mode) to save the power consumption, since putting the disk drive apparatus in such a mode during an idling period has little effect on the performance thereof. Japanese Laid-Open Patent Publication No. 8-255409 discloses a method for efficiently reducing the power consumption of the motor by decreasing the rotational speed of the disk motor in two steps in the sleep mode. Thus, it is possible to save the power consumption of the disk drive apparatus by reducing the rotational speed of the disk motor when a read/write operation is not being performed.
Japanese Laid-Open Patent Publication No. 11-185414 discloses a magnetic disk drive apparatus in which the magnetic head (pickup) is moved away from the center of the disk when a read/write operation is not being performed in order to reduce the windage loss on the rotating disk. According to Japanese Laid-Open Patent Publication No. 11-185414, when the head is near the outer periphery of the disk, as compared to when it is near the center of the disk, the airflow generated by the rotation of the disk is less likely to be disturbed, whereby it is possible to reduce the windage loss and thus the power consumption of the disk motor.
The conventional magnetic disk drive apparatus disclosed in Japanese Laid-Open Patent Publication No. 11-185414 will now be described with respect to FIG. 12. FIG. 12 illustrates a head disk assembly (hereinafter referred to as an xe2x80x9cHDAxe2x80x9d) of a magnetic disk drive apparatus 100 with a magnetic disk 101 loaded therein. The magnetic disk 101, as a storage medium, is secured on the rotating member of a spindle motor 102 by a disk clamp 103, so that the magnetic disk 101 is rotated by the rotation of the spindle motor 102.
The magnetic disk drive apparatus 100 includes a magnetic head 104 for writing information onto the magnetic disk 101. The magnetic head 104 is pivotally secured on a pivot 106 via a head arm 105. The magnetic head 104 can be moved substantially in the radial direction of the magnetic disk 101 by moving the head arm 105 by using a voice coil motor 112 including a coil section 107 and a magnetic circuit 108. The spindle motor 102, the pivot 106 and the magnetic circuit 108 are secured to a base 109.
The magnetic disk drive apparatus 100 rotates the magnetic disk 101 counterclockwise by driving the spindle motor 102. The rotation of the magnetic disk 101 generates an airflow 110 in a direction according to the rotation direction of the magnetic disk 101, as indicated by an arrow in FIG. 12.
While the disk is rotating, the magnetic head 104 is moved as necessary between the outer periphery and the inner periphery of the magnetic disk 101 by pivoting the head arm 105 about the pivot 106. When the magnetic head 104 is near the outer periphery of the magnetic disk 101, a gimbal 111 and the head arm 105 are outside the magnetic disk 101. In such a position, the gimbal 111 and the head arm 105 do not interfere with the passageway of the airflow 110 generated by the rotating magnetic disk 101, thereby reducing the windage loss.
When the magnetic head 104 is at a position within the disk area that is not near the outer periphery of the magnetic disk 101, the gimbal 111 and the head arm 105 as well as the magnetic head 104 are within the area of the magnetic disk 101, thereby narrowing the passageway of the airflow 110 generated by the rotating magnetic disk 101 and thus disturbing the airflow 110. As a result, the windage loss on the rotation of the magnetic disk 101 increases, thereby increasing the power consumption of the disk drive apparatus.
The operations of the magnetic head 104, the spindle motor 102, the voice coil motor 112 for moving the magnetic head 104, etc., are controlled by an upper-level device (not shown). The upper-level device outputs signal for controlling the operations of the magnetic head 104, the spindle motor 102, etc., so as to read/write information from/onto the magnetic disk 101. When the magnetic disk drive apparatus 100 receives a read command from the upper-level device, a seek operation is performed to move the magnetic head 104 to an intended track, and information is read by the magnetic head 104 from the intended track.
After completion of a read command, for example, the magnetic disk drive apparatus 100 performs a power saving operation as follows. If, after completion of the read command, the magnetic head 104 is on the inner periphery side with respect to a predetermined radial distance (e.g., a distance equal to two thirds of the radius of the magnetic disk 101) from the center of the magnetic disk 101, and if another command is not issued from the upper-level device within a predetermined period of time after the completion of the read command, then, the magnetic head 104 is moved to the outer periphery side of the magnetic disk 101 with respect to the predetermined radial distance. In order to effectively reduce the power consumption of the spindle motor 102, the magnetic head 104 can be moved as far as possible away from the center of the magnetic disk 101. In order to further reduce the power consumption, the magnetic head 104 can be moved away from the center of the magnetic disk 101 even if the magnetic head 104 is on the outer periphery side of the magnetic disk 101 with respect to the predetermined radial distance after completion of the read command.
As described above, by moving the pickup away from the center of the disk when a read/write operation is not being performed, it is possible to reduce the windage loss occurring while the disk is rotating, thereby reducing the power consumption of the disk drive apparatus.
However, when a power saving operation as described above is employed in order to reduce the power consumption of the disk drive apparatus, the temperature of the pickup (head) is likely to increase. As the rotational speed of the disk is decreased or the pickup is moved away from the center of the disk in order to reduce the disturbance of the airflow, the amount of airflow around the pickup entailed by the rotating disk is reduced, thereby reducing the air-cooling effect on the pickup.
When the temperature of the pickup exceeds an acceptable range, the performance of the pickup may be lowered, the operating life of the pickup may be shortened. In the case of an optical disk from/onto which information is read/written with laser beam, the temperature of a laser diode unit (hereinafter referred to also as an xe2x80x9cLDUxe2x80x9d) or a laser diode driver (hereinafter referred to also as an xe2x80x9cLDDxe2x80x9d) provided in the pickup for generating laser beam may increase to a very high temperature. The performance of an LDU is significantly lowered by overheating. Therefore, it is very important to prevent the pickup from being overheated. Accordingly, in many of such disk drive apparatuses in the prior art, the inside of the disk drive apparatus is cooled by air by using a cooling fan, or the like.
As described above, when one attempts to reduce the windage loss occurring while the disk is rotating in order to reduce the power consumption of the disk drive apparatus, the pickup is more likely to be overheated. Therefore, it has been difficult to reduce the windage loss on the disk while preventing the pickup from being overheated.
It is therefore an object of this invention to provide a disk drive apparatus capable of preventing a pickup from being overheated while minimizing the power consumption of the disk drive apparatus.
An inventive disk drive apparatus includes: a motor for rotating a disk-shaped storage medium; a pickup for performing at least one of a write operation of writing information onto the storage medium and a read operation of reading information from the storage medium; a rotation controller for controlling a rotational speed of the storage medium; and an overheat detector for detecting overheating of the pickup, wherein: the pickup is cooled by using an airflow generated by the rotation of the storage medium; and when the overheat detector detects overheating of the pickup, the rotation controller increases the rotational speed of the storage medium to perform an operation of increasing an efficiency of cooling the pickup.
Another inventive disk drive apparatus includes: a motor for rotating a disk-shaped storage medium; a pickup for performing at least one of a write operation of writing information onto the storage medium and a read operation of reading information from the storage medium; a pickup-moving device for moving the pickup between a center of rotation of the storage medium and an outer periphery of the storage medium; and an overheat detector for detecting overheating of the pickup, wherein: the pickup is cooled by using an airflow generated by the rotation of the storage medium; and when the overheat detector detects overheating of the pickup, the pickup-moving device moves the pickup toward the center of rotation of the storage medium to perform an operation of increasing an efficiency of cooling the pickup.
In a preferred embodiment, the overheat detector includes a temperature measuring device for measuring a temperature of the pickup.
In a preferred embodiment, the overheat detector includes a rotational speed detector for detecting a rotational speed of the storage medium, wherein overheating of the pickup is detected based on an output of the rotational speed detector.
In a preferred embodiment, the overheat detector further includes a timer for measuring a time duration for which the rotational speed of the storage medium is within a predetermined rotational speed range, wherein overheating of the pickup is detected based on the output of the rotational speed detector and an output of the timer.
In a preferred embodiment, the overheat detector includes a position detector for detecting a position of the pickup, wherein overheating of the pickup is detected based on an output of the position detector.
In a preferred embodiment, the overheat detector further includes a timer for measuring a time duration for which the position of the pickup is within a predetermined position range, wherein overheating of the pickup is detected based on the output of the position detector and an output of the timer.
In a preferred embodiment, the disk drive apparatus further includes a cartridge detector for determining whether the storage medium is connected to the motor while being accommodated in a cartridge.
In a preferred embodiment: when the cartridge detector determines that the storage medium is connected to the motor while being accommodated in the cartridge, an operation of increasing the efficiency of cooling the pickup is performed; and when the cartridge detector determines that the storage medium is connected to the motor while being not accommodated in the cartridge, an operation of increasing the efficiency of cooling the pickup is not performed.
In a preferred embodiment, when the pickup does not receive a control signal from an upper-level device for controlling the pickup to read information from the storage medium or write information onto the storage medium, an operation of increasing the efficiency of cooling the pickup is performed.
In a preferred embodiment: the overheat detector includes a position detector for detecting a position of the pickup; the storage medium is rotated while being accommodated in a cartridge having an opening; the pickup includes a heat generating portion; and when the position detector determines that a position of the heat generating portion of the pickup is outside the opening of the cartridge, the pickup-moving device moves the pickup toward the center of rotation of the storage medium.
In a preferred embodiment, the heat generating portion is a laser device.
In a preferred embodiment, when the overheat detector detects overheating of the pickup, the pickup-moving device moves the pickup to a vicinity of a position that is closest to the center of rotation of the storage medium within a range of motion of the pickup.
In a preferred embodiment: the storage medium includes a read/write region from or onto which information can be read or written; and when the overheat detector detects overheating of the pickup, the pickup-moving device moves the pickup to a vicinity of a position that is closest to the center of rotation of the storage medium within the read/write region of the storage medium.
Still another inventive disk drive apparatus includes: a motor for rotating a disk-shaped storage medium; a pickup for performing at least one of a write operation of writing information onto the storage medium and a read operation of reading information from the storage medium; a pickup-moving device for moving the pickup between a center of rotation of the storage medium and an outer periphery of the storage medium; a rotation controller for controlling a rotational speed of the storage medium based on a position of the pickup; and an overheat detector for detecting overheating of the pickup, wherein: the pickup is cooled by using an airflow generated by the rotation of the storage medium; and when the overheat detector detects overheating of the pickup, the pickup-moving device moves the pickup toward the center of rotation of the storage medium and the rotation controller increases the rotational speed of the storage medium to perform an operation of increasing an efficiency of cooling the pickup.
Still another inventive disk drive apparatus includes: a motor for rotating a disk-shaped storage medium; a pickup for performing at least one of a write operation of writing information onto the storage medium and a read operation of reading information from the storage medium; a rotation controller for controlling a rotational speed of the storage medium; a pickup-moving device for moving the pickup between a center of rotation of the storage medium and an outer periphery of the storage medium; and an overheat detector for detecting overheating of the pickup, wherein: the pickup is cooled by using an airflow generated by the rotation of the storage medium; and when the overheat detector detects overheating of the pickup, an operation of increasing an efficiency of cooling the pickup by the airflow is performed.
The term xe2x80x9cpickupxe2x80x9d as used herein refers to any device that can be moved across the surface of a disk while facing the disk so as to perform at least one of a write operation of writing information onto the disk and a read operation of reading information from the disk. The pickup as used herein may be a write-only pickup, a read-only pickup or a read/write pickup, and includes an optical device, a magnetic device, and an electric circuit, for example. In the case of an optical disk drive apparatus, the pickup (optical pickup) may include, for example, a laser diode unit for generating laser beam, a laser diode driver for driving the laser diode unit, and a head amplifier for amplifying, and converting into a voltage signal, an electric signal that is obtained by receiving and converting reflected laser beam from the disk. In the case of a magnetic disk drive apparatus, the pickup may, include, for example, a magnetic head for performing at least one of an operation of generating a magnetic field and an operation of detecting a magnetic field, and a head amplifier for amplifying an electric signal obtained by the detected magnetic field.